The discovery of optical solitons, which can be understood as temporally and spectrally stationary optical states, has enabled numerous innovations most notably supercontinuum light sources, which have become ubiquitous in both fundamental and applied science. Here, we report on the first experimental evidence for hybrid solitons - a new type of solitary wave, which emerges as a consequence of a strong non-instantaneous nonlinear response in CS2-filled liquid-core optical fiber. Octave-spanning supercontinua in the mid-infrared were observed when pumping the hybrid waveguide with a 460 fs laser (1.95 _m) in the anom21alous dispersion regime at nanojoule-level pulse energies. A detailed numeric analysis well correlated with the experiment deduces clear indicators for emerging hybrid solitons reveal23ing their impact on bandwidth, onset energy, and noise characteristic of the supercontinua. Our study highlights liquid-core fibers as a promising platform for fundamental optics and applications towards novel coherent and reconfigurable light sources.